Friends and family-members of those slain or still missing following Friday's Christchurch mosque massacre are facing an heart-wrenching wait for news.

One Bangladeshi told SBS News his friend, who had been at one of the mosques when the deadly attacks began, remained unaccounted for.

He said he was now playing a "waiting game" to hear any news of his mate.

"One of my friends, he's not on that list, and he's not in the hospital list, so that's shocking - where he is?" he said.

"We are 100 per cent sure he was in the mosque - his family back home want to know if he's alive or dead.

Friends of a missing man grieve outside a refuge centre in Christchurch.

"The men who were praying with us died, our left side, our right side.....so we are feeling very very sad."

All 50 bodies have now been removed from the mosques, and the city's Muslim community has urged authorities to quickly release the remains to family for fast burials in adherence with customs.

Prime Minister Jacinda Ardern confirmed that the first of the bodies would be released on Sunday afternoon.

One man told SBS News he was now left waiting to hear any news of his friend, who he feared was inside one of the mosques.

Work by heavy machinery and a large crew to prepare graves was under way on Sunday, not far from where the second of shootings took place.

The country is already mourning, with many people grieving at makeshift memorials in Christchurch, while vigils and church services are being held elsewhere.

An interfaith prayer session outside the Christchurch memorial, following the shooting.

NZ Police Commissioner Mike Bush revealed on Sunday the body of the 50th victim had been found in the Masjid Al Noor mosque on Deans Avenue on Saturday night.

Mr Bush said police, pathologists and coroners were working to ensure families could claim their loved ones as soon as possible.

"We have to be absolutely clear on cause of death and confirm their identity before that can happen," he said.

"But we are so aware of the cultural and religious needs. So we are doing that as quickly and sensitively as possible."

Mohammed Abdelhalim described to Radio NZ losing a number of childhood friends, three with young families, in the attack.

"We were ... family people with no malice, no aggression and nothing but love for this country," he said.

"We just want our loved ones back now. We want to lay them to rest."

Another 50 people were wounded in the shooting sprees, with around 36 still in hospital on Sunday.

Four-year-old Elin Daraghmeh is among the dozen people who are still listed in a critical condition. Her father Waseem, 33, is said to be in a stable condition.

Christchurch Hospital Head of Surgery Dr Greg Robertson described how he watched the first victims arrive in private cars, followed by ambulance after ambulance.

"This is not something that we expected to see in our environment," he told reporters.

Mourners link arms in Hagley Park near the Al Noor mosque.

"We do see gunshot wounds. We do see all these type of injuries, but, you know, 40 or 50 people in a day is more than what we should see."

Australian man Brenton Tarrant remains the only person to be charged with murder over the Christchurch mosques massacre that has claimed the lives of 50 people.

Police have been piecing together what's been described as a complex event, following the shocking shooting spree on Friday which authorities have confirmed was a terror attack.

Mr Bush on Sunday told reporters four other people arrested during Friday's police operation attack have either been released or charged with "tangential" offences.

A man and a woman were held in custody while police investigated their involvement, if any, in the two shooting attacks. Mr Bush said the woman had been released without charge.

"The man in the vehicle has been charged with firearms offences. At this point, we do not believe that they were involved in these attacks," Mr Bush.

A third man - aged 18 - has also been charged, but is not believed to have been directly involved in the attacks.

"What I can say is that an 18-year- old man will appear in court on Monday but that arrest was tangential to this matter and we do not believe that he was involved in this attack either," Mr Bush said.

A fourth person taken into custody has since been released.

Muslim community members have raised concerns that the time taken to remove the bodies from the mosques would comprise the burial process.

Mr Bush said police, pathologists and coroners were working to ensure families could claim their loved ones as soon as possible.

"We have to be absolutely clear on cause of death and confirm their identity before that can happen," he said.

"But we are so aware of the cultural and religious needs. So we are doing that as quickly and sensitively as possible."

Brenton Tarrant in court, charged with murder over the Christchurch mosque massacre.

The attack is the worst shooting in the country's history and has seen its threat level raised to high for the first time.

Police say they will continue guarding mosques around the country until further notice. Helicopters have been hovering overhead in Christchurch since, while heavily-armed officers patrol streets.

Sadly, Police can confirm this morning that during the scene examination of the Deans Avenue Mosque yesterday, the body of a further victim was found.